Device providing an improved keypad assembly for a portable electronic device

Abstract

A keypad assembly for a wireless device is provided. The keypad assembly comprises a circuit board, a keypad portion, a light guide, and at least one friction device. The keypad portion has a number of keys for physical actuation, each of the keys having an actuator post attached to a back side of the key. The circuit board has one or more electrical switches, the electrical switches corresponding to keys of the keypad. The light guide is located between the keypad portion and the circuit board. The light guide has a number of holes formed therein. The holes provide paths for respective actuator posts of the keys to travel through to contact the respective electrical switches on the circuit board. The at least one friction device is located in at least one of the holes of the light guide. The friction device provides a physical barrier limiting movement of the actuator post in a direction normal to the direction of actuation and the friction device applies friction to the side of the actuator post, thereby resisting movement of the actuator post in the direction of actuation.

1 . A keypad assembly for a wireless device, the keypad assembly comprising:
 a keypad portion having a number of keys for physical actuation, each of the keys having an actuator post attached to a back side of the key;   a circuit board having one or more electrical switches, the electrical switches corresponding to the keys of the keypad;   a light guide located between the keypad portion and the circuit board, the light guide having a number of holes formed therein, the holes providing paths for respective actuator posts of the keys to travel through to contact the respective electrical switches on the circuit board; and   at least one friction device located in at least one of the holes of the light guide, the friction device providing a physical barrier limiting movement of the actuator post in a direction normal to a direction of actuation, the friction device applying friction to at least one side of the actuator post and resisting movement of the actuator post in the direction of actuation.   
   
   
       2 . The keypad assembly according to  claim 1 , wherein the at least one friction device comprises a grommet having at least one interference zone. 
   
   
       3 . The keypad assembly according to  claim 2 , wherein the grommet is round and has an outside circumference approximately equal to or greater than an inside circumference of the holes in the light guide. 
   
   
       4 . The keypad assembly according to  claim 3 , wherein the grommet is press-fit into the hole. 
   
   
       5 . The keypad assembly according to  claim 3 , wherein the grommet is moulded into the holes using a two-shot moulding process. 
   
   
       6 . The keypad assembly according to  claim 3 , wherein the grommet has a number of interference zones selected from the group consisting of one, two, three, and four. 
   
   
       7 . The keypad assembly according to  claim 6 , wherein the interference zones are equally spaced about an inside circumference of the grommet. 
   
   
       8 . The keypad assembly according to  claim 3 , wherein the interference zones are raised portions that extend inwardly from an inside circumference of the grommet, thereby decreasing the inside circumference of the grommet over a portion of the inside circumference of the grommet. 
   
   
       9 . The keypad assembly according to  claim 8 , wherein the interference zones extend in length anywhere from a portion of an axial length of the grommet to the entire axial length of the grommet. 
   
   
       10 . The keypad assembly according to  claim 1 , wherein the at least one friction device comprises one or more members attached to an inside circumference of the holes of the light guide. 
   
   
       11 . The keypad assembly according to  claim 10 , wherein the number of members in a single hole is selected from the group consisting of one, two, three, or four. 
   
   
       12 . The keypad assembly according to  claim 11 , wherein the members are equally spaced about the inside circumference of the hole. 
   
   
       13 . The keypad assembly according to  claim 11 , wherein the members form raised portions that extend inwardly from the inside circumference of the hole, thereby decreasing the inside circumference of the hole over a portion of the inside circumference of the hole. 
   
   
       14 . The keypad assembly according to  claim 13 , wherein the members extend anywhere in length from a portion of an axial length of the hole to the entire axial length of the hole. 
   
   
       15 . The keypad assembly according to  claim 1 , further comprising:
 a bezel Frame located in front of the keypad portion, the bezel frame defining an opening in the frame for each of the keys; and   one or more light emitting diodes connected to the circuit board for providing light to the light guide,   wherein the switches on the circuit board are dome switches.   
   
   
       16 . A device for use in a hole of a light guide of a keypad assembly, the light guide being located between a keypad and a circuit board, the hole providing a path for an actuator post of a key of the keypad to travel through to contact a respective switch on the circuit board, the device comprising:
 a grommet having at least one interference zone, the grommet having an outside dimension approximately equal to or greater than an inside dimension of the hole, the interference zones being raised portions that extend inwardly from the inside dimension of the grommet, thereby decreasing the inside dimension of the grommet over a portion of the inside dimension of the grommet.   
   
   
       17 . The device according to  claim 16 , wherein the grommet is round, the outside dimension of the grommet being an outside circumference, the inside dimension of the hole being an inside circumference, the grommet having an axial length, and the interference zones extending in length anywhere from a portion of an axial length of the grommet to the entire axial length of the grommet. 
   
   
       18 . A device for use in a hole of a light guide of a keypad assembly, the light guide being located between a keypad and a circuit board, the hole providing a path for an actuator post of a key of the keypad to travel through to contact a respective switch on the circuit board, the device comprising:
 one or more members attached to an inside dimension of the hole of the light guide, the members forming raised portions that extend inwardly from the inside dimension of the hole, thereby decreasing the inside dimension of the hole over a portion of the inside dimension of the hole.   
   
   
       19 . The device according to  claim 18 , wherein the hole is round and has an axial length, the inside dimension of the hole being an inside circumference, and the members extending anywhere from a portion of the axial length of the hole to the entire axial length of the hole. 
   
   
       20 . A portable wireless device having a keypad assembly, the keypad assembly comprising:
 a keypad portion having a number of keys for physical actuation, each of the keys having an actuator post attached to a back side of the key;   a circuit board having one or more electrical switches, the electrical switches corresponding to the keys of the keypad;   a light guide located between the keypad portion and the circuit board, the light guide having a number of holes formed therein, the holes providing paths for respective actuator posts of the keys to travel through to contact the respective electrical switches on the circuit board; and   at least one friction device located in at least one of the holes of the light guide, the friction device providing a physical barrier limiting movement of the actuator post in a direction normal to the direction of actuation and the friction device applying friction to the side of the actuator post, thereby resisting movement of the actuator post in the direction of actuation.